1. Field of the Invention
This invention relates to the demetalation of heavy petroleum residua. In the novel process disclosed herein heavy petroleum residua is contacted with large pore solid materials adapted to selectively adsorb metal-containing molecules from the residua.
2. Description of the Prior Art
Residual petroleum oil fractions containing relatively high proportions of metals, such as those heavy fractions produced by atmospheric and vacuum crude distillation columns are generally unsuitable as charge stocks for processes such as hydrocracking. Principal metal contaminants are nickel and vanadium compounds, with iron and copper compounds also sometimes present. Additionally, trace amounts of zinc and sodium containing compounds may also be present. These metals, when present in residual oils, are associated with very large hydrocarbon molecules, the metal contaminants are typically large organometallic complexes such as metal porphyrins. The prior art has utilized many methods with varying degrees of success to render such residua suitable for refining processes such as hydrocracking.
Molecules containing metals such as nickel and vanadium which are normally present in heavy resids tend to associate with themselves and with other polyaromatic systems present and form conglomerates which react only with difficulty, therefore, demetalation processes in accordance with the prior art usually involve relatively severe conditions of time and temperature and also usually consume a considerable amount of hydrogen.